ADHD or Depression? Key Differences

Cannot concentrate. Cannot get started. Tired, behind on everything, and starting to feel like a failure. That description fits ADHD, it fits depression, and it fits adults who have both. The conditions are treated differently, so mistaking one for the other can mean months of treatment that does not touch the main problem. This page is a side-by-side comparison of how they differ. For how treatment is ordered when both are present, see the full guide article on ADHD and depression in adults.

Where the symptoms overlap

The National Institute of Mental Health (NIMH) lists these among the signs of depression: difficulty concentrating, remembering or making decisions; feelings of irritability, frustration or restlessness; greater impulsivity; difficulty sleeping or oversleeping; and inability to meet responsibilities. Each has a counterpart in NIMH's description of adult ADHD, which includes distractibility, forgetfulness, restlessness, trouble finishing projects and choosing immediate rewards over later ones.

So a symptom checklist filled out during a low stretch can point toward ADHD when the cause is mood, and a person with lifelong ADHD who is worn down can look depressed. The two questions that separate them are about time: when did this start, and does it come and go?

Side by side

The rows come from NIMH's publications on depression and on adult ADHD. A 2017 review in BMC Psychiatry makes the same practical point: a depressed mood that stays fixed, changes in appetite, and thoughts of suicide are the features that most help identify depression in someone who also has ADHD.

The harder case: long-lasting, low-grade depression

Major depression arrives as an episode, which makes the timeline fairly easy to read. Persistent depressive disorder (also called dysthymia) is harder. NIMH describes it as less severe symptoms that last much longer, usually at least two years. Someone who has felt flat and low for most of adult life may not remember a time before it, just as someone with ADHD cannot remember a time before distraction. In that situation, school-age history matters most: concentration problems that were visible in elementary school, before any low mood, point toward ADHD, possibly with depression on top.

How often they occur together

The National Comorbidity Survey Replication, published in 2006, found that in the previous 12 months 18.6% of adults with ADHD had major depressive disorder and 12.8% had dysthymia, compared with 7.8% and 1.9% of adults without ADHD. The sample was adults aged 18 to 44 with wide margins of error, so the figures are approximate.

The overlap runs the other way too. The 2017 BMC Psychiatry review cites a study in which 28% of adults referred to a specialty clinic for mood and anxiety assessment had ADHD that had not been detected. In that study, the number of SSRI antidepressants a person had already tried was one of the factors that predicted undetected ADHD. The review's explanation: serotonin-based medications alone would not be expected to improve ADHD symptoms. That figure comes from one referral clinic, not the general population, but the pattern is worth knowing if you have tried several antidepressants and still cannot focus.

The ADHD guideline from NICE, the UK's National Institute for Health and Care Excellence, tells clinicians that adults with a mental health condition may have a higher prevalence of ADHD and that every ADHD assessment should include coexisting conditions.

Low mood that follows from ADHD

The BMC Psychiatry review describes a third possibility. Some depressive symptoms in adults with ADHD may reflect demoralization from living with ADHD, rather than a separate depressive disorder. Years of being told to try harder can wear anyone down. When that is the main story, mood may lift as ADHD is recognized and managed. When it is a true depressive episode, it needs treatment of its own. Deciding which is the case is a judgment for the evaluating clinician, and both can be true at once.

Other things that can look like either

• Bipolar disorder. NIMH notes that bipolar disorder includes depressive episodes as well as manic or hypomanic ones. Anyone being assessed for depression or ADHD should be asked about periods of unusually high energy and little need for sleep. See ADHD or bipolar disorder?
• Medical causes. NIMH says some medications and medical conditions, such as viruses or thyroid disorders, can cause the same symptoms as depression, and that a provider can rule these out with an exam, an interview and lab tests. The page on ADHD or thyroid problems covers this.
• Anxiety. Depression and anxiety often travel together, and both overlap with ADHD. See ADHD or anxiety?

Why the answer matters for treatment

NIMH describes depression treatment as typically psychotherapy, medication or both, and the most common adult ADHD treatments as medication, usually stimulants, and psychotherapy. A 2026 study of 13,693 adults with ADHD treated for depression and anxiety in England's NHS Talking Therapies found moderate to large reductions in depression symptoms, though results were somewhat less favorable than in matched adults without ADHD. In other words, depression treatment works for people with ADHD, and ADHD may affect how well it works. Which condition to address first depends on severity and safety, and that decision is laid out in ADHD and depression in adults.

Dr. Shershow's adult ADHD evaluation checks whether depression explains the symptoms, occurs alongside ADHD, or both. It covers current symptoms, childhood and work history, sleep, medications and substances, and ends with what was found and the treatment options that fit. The ADHD and depression evaluation page explains how that works for adults in New York and New Jersey.

Questions worth answering before a visit

• Were focus and organization a problem in elementary school, before any low mood?
• When your mood is good, does your concentration improve?
• Have you had distinct periods of depression? How long did they last, and what helped?
• Which antidepressants have you tried, and what changed and what did not?
• Have you ever had days of unusually high energy with little need for sleep?
• What is your alcohol, cannabis and other substance use?

When to talk to a clinician

If low mood, poor concentration or both have been getting in the way of work, home or relationships, these are signs worth discussing with a clinician, and you do not need to know which condition it is beforehand. A screener such as the adult ADHD self-test can help you put your experience into words, but it does not diagnose ADHD or depression. To see what an evaluation involves, read about adult ADHD testing in NYC or adult ADHD testing in New Jersey.

If you are thinking about suicide or are worried about someone else, call or text 988, the Suicide and Crisis Lifeline, which NIMH lists for anyone who is struggling. In a life-threatening emergency, call 911.